Tian Jin Rong Da Jian Ce You Xian Gong Si

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Brass dezincification corrosion test

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Place of Production 天津
Product Category 工程监理和第三方检验
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Brass dezincification corrosion test, corrosion resistance of brass dezincification of brass dezincification corrosion detection, detection mechanism, brass dezincification corrosion testing mechanism, brass dezincification detection
Tianjin Rong Da Testing Co., Ltd. contact: Wang Jingfu
Cell phone: 13102238283 QQ:3144667033
Telephone: 022-23892103
On the dezincification mechanism at home and abroad have done some research and put forward various conclusions, but it is not very perfect, the main theory of preferential dissolution and dissolution deposition mechanism, divacancy mechanism and percolation mechanism. Then let's give a brief introduction to these mechanisms.
First, preferential dissolution and dissolution of the repeated deposition mechanism. That the preferential dissolution mechanism, brass corrosion process, zinc alloy surface from the brass alloy and the preferential dissolution of zinc by internal vacancy diffusion to dissolve, the positive potential of copper remains, a copper layer is loose. But this kind of theory is difficult to explain the contradiction between the depth of brittle crack caused by zinc and the low diffusion coefficient of zinc at room temperature. The selective dissolution of zinc in the brass surface contact with the solution, the corrosion of zinc alloy is compensated by the lattice diffusion of zinc atoms, zinc and zinc by selective erosion in the forefront of this activity, continue to move forward. In accordance with the author's point of view, the zinc free phase only occurs in the skeleton structure of the original brass matrix, which allows the free zinc ion diffusion and the zinc free resistance of brass depends on the degree of difficulty of the zinc outer electrons leaving the zinc atom.
Second, dissolved redeposition mechanism that brass on the surface of zinc and copper with zinc dissolved in the solution, and copper on the surface near the dissolution at the rapid precipitation and re deposited on the substrate, but this mechanism cannot explain satisfactorily impossible when dissolved copper zinc removal phenomenon. Because the potential of zinc dissolution is much lower than the anodic dissolution potential of copper, copper and zinc can not be dissolved in any case at the same time. Were studied in sulfuric acid, in the initial stage due to the establishment of primary battery (Cu-Zn), preferential dissolution of zinc in the solution, but when the porous copper copper oxide film formed on the electrode surface, zinc removal rate decreased, while copper and zinc dissolution. The dissolution rate of zinc by diffusion through the lattice velocity control in this stage, the dissolution rate of copper because of the formation of CuO films decreased, the decisive position depends on the corrosion conditions, such as selective dissolution in dilute hydrochloric acid occurs in zinc, but high concentrations of copper re precipitated occurs or hydrochloric acid in seawater the dezincification corrosion. In addition, the mechanism of zinc removal was affected by the dissolution temperature and the length of the immersion period. Whether copper and zinc can be dissolved at the same time can be predicted by overlapping the potential -pH diagram.
And the method to prevent the corrosion of brass from zinc, mainly from the metallurgical aspects, followed by the improvement of the environment can be considered. To improve the corrosion environment, can be used for cathodic protection, adding corrosion inhibitor, reducing medium corrosion resistance, but due to working conditions, and can not completely inhibit the removal of zinc brass. The cure of the method is to improve the ability of brass by metallurgical method, which is an absolute good method to prevent the corrosion of brass.